Forum tips

Writing in Hebrew
If you post a forum message in Hebrew (or English mixed with Hebrew), add[[div style="direction:rtl;"]]
before your message, and[[/div]]
after it (each on a separate line).

Including Python code
When including python code in your message, if you don't want to lose the indentation, and also benefit from syntax highlighting, add[[code type="python"]]
before the code, and[[/code]]
after it (each on a separate line).

BoldPut ** before and after the text: a**b**c —> abc

UnderlinePut __ before and after the text: a__b__c —> abc

Raw textPut @@ before and after the text, to ignore formatting: @@a**b**c@@ --> a**b**c

Your Hebrew text was a bit garbled, so the answer here refers to what I understood:

Given a code with d = ∆(C), when you receive a word $z \in \{0,1\}^n$ that is not a codeword, yet
is at a distance $\leq d-1$ from some codeword, you can identify that this is not a codeword, namely some errors
occurred in the transmission. Note that this does not mean one can correct d-1 errors.

Given a code with d = ∆(C), one cannot detect d errors, since d errors could change one codeword to another.